Rigid foams made from filled polyols are known. Such foams are typically produced by reacting a polyisocyanate with an isocyanate reactive material such as polyol in the presence of a blowing agent.
In recent years, the substantial increases in costs of the basic materials used to make foam, has encouraged the development and use of filler materials to reduce the amount of the basic materials used and the weight of the finished materials. One of the suggested filler materials and insulating materials utilizes hollow microspheres.
High loadings of inert and/or inorganic fillers pose several limitations on convention flexible and rigid foam processing methods: 1) high intrinsic viscosity; 2) difficult to completely wet-out particles; and 3) unstable dispersion leads to agglomeration and/or settling. High loadings of fillers, however, offer some very interesting potential benefits: 1) inexpensive; 2) offer ability to encapsulate additives; 3) improve compressive strength; and 4) alter energy absorbing capability.
The use of hollow polymeric microspheres as a filler in rigid boardstock polyol is disclosed in U.S. Ser. No. 08/909,447. Because of the extremely high viscosities in using fillers, polyol levels containing significant levels of these fillers cannot be processed on conventional boardstock mixing and metering equipment.